1. The Field of the Invention
The present invention relates to delaying travel path sections for changing the pulse durations of laser pulses, an apparatus for producing elongated laser pulses, and a method for extending the length or duration of laser pulses by means of a plurality of delay path sections.
2. Description of the Related Art
The lengthening or elongation of laser pulses is already known. For example, it is used in order to reduce the intensities of laser pulses, since a material to be tested with the help of a pulsed laser could be damaged by a high intensity pulsed laser beam. Also the intense laser pulses could lead to a premature aging of the optics used in lithography. The laser pulse is divided into different partial pulses by means of a beam splitter in order to lengthen the laser pulse. The respective partial pulses are guided over different-length travel path sections (delay loops) and reach an object to be examined or illuminated in succession. U.S. Pat. No. 5,337,333 describes a method of formatting laser pulses in which on or more delay loops are used. The delay loops include a beam splitter and a plurality of reflectors. An elongated laser pulse with reduced peak intensities is produced from a short intense laser pulse.
The prior art apparatuses for extending the duration or lengthening laser pulses are adapted to or designed for respective specific laser systems. They lengthen a given laser pulse to a predetermined pulse width. A combination of the known apparatus with other laser systems, for example of different manufacturers, or of different qualities, is not possible without further effort.